US Patent No. 10,172,132

MOBILE COMMUNICATION SYSTEM AND USER EQUIPMENT


Patent No. 10,172,132
Issue Date January 01, 2019
Title Mobile Communication System And User Equipment
Inventorship Tooru Uchino, Tokyo (JP)
Hideaki Takahashi, Tokyo (JP)
Kazuki Takeda, Tokyo (JP)
Assignee NTT DOCOMO, INC., Tokyo (JP)

Claim of US Patent No. 10,172,132

1. A mobile communication system comprising:a first base station;
a second base station; and
a user equipment connected to the first base station as a master base station,
wherein when a random access procedure toward a cell of the second base station is triggered at the user equipment, the user equipment performs a contention based random access procedure on a secondary cell of the second base station, based upon one of
(a) selecting the secondary cell on which a random access signal is to be transmitted in accordance with an instruction from the first base station;
(b) selecting the secondary cell on which the random access signal is to be transmitted using implicit information in the user equipment; and
(c) determining autonomously at the user equipment the secondary cell on which the random access signal is to be transmitted,
wherein based on the user equipment receiving, from the first base station, a changing instruction that instructs to change a secondary cell of the second base station for the random access procedure, the user equipment stops the ongoing contention based random access procedure toward the second base station.